Cyanuric chloride preparation



Patented Feb. 25,4h 19.47

1 parte CYANURIC CHLORIDE PREPARATION Jack T. Thurston, Riverside,Conn., assignor to,

American Cyanamid Company,

New York,

N. Y., a corporation of Maine ApplicationJuly 11, 1944, Serial No.544,411

6 Claims..A (Cl. i560-248) The present invention is concerned with the lproduction of cyanuric chloride by polymerizing cyanogen chloride. l

It has been found that cyanuric chloride may be lprepared in good yieldand of high purity by polymerizing cyanogen chloride in the presence ofhydrogen chloride as a catalyst, using a mixture of an aliphatic ethersuch as dioxane anda chlorinated hydrocarbon suchv as chloroform as aninert diluent and heat transfer medium for the reaction mixture. Thepolymerization proceeds slowly inasmuch as it is necessary that thereaction mixture be kept at a low temperature, for example from 'to 10C., in order to avoid volatilization lossesof the low-boiling cyanogenchloride. l

It has now'been discovered that the polymerization of cyanogen chlorideusing hydrogen chloride as the catalyst in a diluted reaction mixturecan be carried out in a relatively short space of time by raising .thetemperature of the reaction mixture to the boilingV point of cyanogenchloride or above and at the same time avoiding loss of the cyanogenchloride by having it` form a nonvolatile complex as it enters theyreaction mixture. The latter is accomplished by having present in themixture a quantity of boron fluoride suflicient to form 'the'complexwith the cyanogen chloride as added. While itis believed that;l theboron fluoride forms a complex which is non-volatile at the op-` eratingtemperatures, yet this explanation should not be taken in arestrictedsense. It has been demonstrated however, that without theboron fluoride, a lower operating temperature is necessary if losses ofthe volatile cyanogen chloride are to be kept at a minimum while withboron fluoride higherl temperatures maybe used still without loss ofcyanogen chloride. There isevidence that the boron fluoride doesY notact as a catalyst -as no yield of cyanuric chloride' was obtained in arun omitting the hydrogen chloride but in the presence of boronfluoride.r

Any desirable inert liquid lmay bev usedv as a diluent for the reactionmixture which has the necessary heat transfer properties, so as toprevent the reaction mass from becoming too thick or viscous, and toabsorb the large quantity of exothermic heat generated by thepolymerization. While aliphatic ethers and chlorinated hydrocarbons ingeneralsuch as isopropyl ethenn-butyl ether, butyl cellosolve,diethylcellosolve, .dioxana ethylene dichloride, carbon tetrachloride,chlorobenzene, chloroform and trichloroethylene, are preferred, otheraliphatic ethers and/or chloy rinated hydrocarbons may be used.

2 y Likewise such ldiluents maybe ketones, hydrocarbons, `11i-- triles,-n itrated aromatic compounds and the like or` admixtures thereof, solong as such materials conform to the above definition.

The invention thereforecontemplates the production of cyanuric chlorideby bringing ytogether cyanogen chloride, hydrogen chloride, an inertdiluent,` and boron fluoride, and recovering the cyanuric chloride thusformed. l Y ,y In the drawing,the single vfigure shows a flow sheet ofthe preferred process. I

The hydrogen chloride was dissolved in the di-l In'carrying out thepreferred process, gaseous boron iiuoride and gaseous hydrogen chlorideare dissolved in dioxane in aclosed reaction vessel provided withsuitable means of agitation and temperature control; Chloroform isthenadded, followed by a gradual addition of thecya'nogen chloride. Thereaction mixture is allowed to lwarm slightly, and is heldat atemperature pref-A erably Within the range of 20T-40 C. After theaddition of the cyanogen chloride is completed, thecrystalline cyanuricchlorideis recovered from the reaction mixture by filtration, or bysettling followed by decantation of the mother liquor. The latter stillcontaining some cyanuric chloride may bev returned to the reactionvessel for another make up or cycle.'

The crude product may beV purified by recrystallization from a chlorinederivative of an aliphatic hydrocarbon, such as, for example, carbontetrachloride, chloroform, ethylene dichloride, trichloroethylene or thelike, or by distillation at atmospheric pressure. e f

v v EampleI e y Charge: Y Grams Cyanogen chloiide 120 Hydrogenchlorider.., 20 Dioxane 40 Chloroform 40 Boron fluoride (45% solution inethyl ether) r '281.

oxane which Was cooled in an vicebath. vThe boron fluoride solution andthe chloroform were then added, followed by the addition `of thecyanogen chloride over a period of 4.5 hours, the

l Y 500 cc; of dioxane.Vv

Example 2 Charge: v Grams Cyanogen chloride 2,808 Boron fluoride 265`Hydrogen chloride 235. Dioxane 1,000 Chloroform 500 The gaseous boronuoride and hydrogen ohiog ride were each dissolved in 5700 g. ofwell-cooled dioxane,'placed in a five-liter flask and the chlo-v 1.reform added. The mixture was stirred at about ed on therate ofaddition of the cyanogen chlo- Y ride. The addition of 2808 g. ofcyanogen chlo-Y Vride required four hours, precipitation of the cyanuric-chloride beginning' after 35 minutes,

atwhich time 420 g. of cyanogen chloridel had been added. After theaddition of cyanogen chloride was completed, the reaction mixture wasallowed to stand until the precipitated cyanuric chloride had settled.The supernatant liquor was However, at 30 C;

anogen chloride, was 70.62%.

ture being held at about 30 C. The crude prod--V uct was crock-filtered,and washed with dioxane Y and chloroform. 8820 g. (87.5% yield) ofcyanuric chloride were obtained.

The combined products of cyanuric chloride from the runs of Examples 2to 6 inclusive totaled 20.3 kg. and represented an Y84.2%, yield from24.1 kg. of cyanogen'chloride. l'This combined product was distilled togive 17.02 kg. of pure cyanuric chloride. The distillation yield, basedon Ythe crude product, was 83.8%, While the overall yieldV of purecyanuric chloride, based on cy- Example 7 A solution consisting of 32.3g. of boron uoride dissolved in 65.5 g. of isopropyl ether was combinedwith a solution consisting of 5.9 g. of hy-` 1 drogen chloride dissolvedin 19 g. of isopropyl then siphoned olf and the solid was washedwith l YThe crude yield wasV 2089`g. or 73.5%. l

" l Example 3 `.The supernatantY mother liquor and washings from the runof Example 2 werereused. 3222 Vg.

Yofl cyanogenlchloride being added overV a vlive hour period, whilekeeping the reaction temperature at -35? C. and the cooling bath at 3-7.C. TheY precipitated solid was filtered, washed with 5001cc.' .ofdioxane, followed by 400 cc. of chloreform'.V The yield was 2657 g.(82.4%) of crude cyanuric chloride. l Y i 'Example 4 l y Re.-uSe,.of thesupernatant mother liquor and washings 'from the run of Example 3 andthe addition of. 2868 g. of cyanogen chloride over a A solutionconsisting of v509 g. of boron fluo-l ride dissolved in 800 g. ofdioxane was combined.

with a solution consisting of 310g. of hydrogen chloride dissolved in800 g. of dioxane. 900 g. of chloroform'were added,` the solution beingagi-` tated and held at about v30 C.l 5136 g. of cyanogen' chloride weregradually added over a period of about 5 hours, the temperature of thetered, 'washed with 500 cc. of dioxane, and then followed by 300 cc. ofchloroform; `4,550 g. (88.6% yield) of the product were obtained, melt#ing` at 145 C.: V Y y e Example 6- flpuringarperiod'lof. hours`,'1 0,080g. of cyanogenrchloride were added to the supernatant mother liquor'andwashings kfrom the run of Ex,

V ample 5, thetemperature'" of the'reaon mixreaction mixture being keptbetween '30 'and 35 C. The precipitated cyanuric chloride was filether.A mixture consisting of 72.4 g. of yisopropyl ether and g. Vof carbonitetrachloride was added, the mix being stirred and warmed to about 35"C. Y then added during aperiod of one hour and thirty minutes, thetemperature of the charge being held between 35 and'40 C. The resultingmix-Y ture, after standing over night (about 16 hours)V at roomtemperature, was filtered. 90 g. of 'cy-V anuric chloride wereobtained.Y Y

Example 8 A solution consisting of 18 g. of boronuoride dissolved in15.3 g. of diethyl Cellosolve.v (ethylene glycol diethyl ether) Wascombined with a solution consisting of 3.3 g/of hydrogen chloridedissolved in 11 g. of diethyl Cellosolve. consisting of 50.8 rg.- ofdiethyl Cellosolve and 33.4 g. of chlorobenzene was added, the mix beingstirred and kept at about 30 C. 123g.'of cyanogen chloridewere thenadded during a period/of 35 minutes, the temperature of thecharge beingheld between 30 and 35 C.y After standing sev# eral hours at roomtemperature, the. precipitated cyanuric chloride was removed byltration. The

crude yield was 69%.v

Y Example 9- A lsolution consisting of 10 g. of boron fluoride dissolvedin 17.2 g. of n-butyl ether was combined with a solution consisting ofV2.7g. of hydrogen chloride dissolved in 13 g. of n-butyl ether. Amixture consisting of Y26.5 g. .of n-butyl ether and 19.8 g. of ethylenedichloride was added, the mix beingstirred and maintained at about 30C.- 123 g. of cyanogen chloridewerethen added during a period of onehour and 15 minutes, the temperature of the ycharge being held between23 and 28 C. After the addition of the cyanogen chloride was completed,the reaction mixture was filtered to recover the precipitated cyanuricchloride..Y K-

Y j Example 10 l. solution consisting of 311g. of boronv fluoridethenadded during a period of one houly'the terniV perature of thechargev being held between 30 and 35i` C; Afterstanding.severalhourslatlllopni temperature, the precipitated 'cyan'uricchloride 123 g. of cyanogen chloridewere A mixture was removed byltration. A 71% yield of the product was obtained.

Cyanuric chloride is of particular value as an intermediate in thepreparation of triazine compounds which may i'lnd application in thefield of dyestuis, explosives, synthetic resins, rubber and medicine.

While the invention has been describedwith particular reference tospecic embodiments, it is to be understood that it is not to be limitedthereto, but is to be construed broadly and restricted solely by thescope of the appended claims.

I claim:

1. A method of producing cyanuric `chloride which comprises mixingcyanogen chloride, hydrogen chloride, an inert liquid diluent and boronuoride at substantially atmospheric pressures, and recovering thecyanuric chloride.

2. A method of producing cyanuric chloride which comprises mixingcyanogen chloride and a mixture consisting of hydrogen chloride, boronuoride, an aliphatic ether and a. chlorinated hydrocarbon atsubstantially atmospheric pressures, and vrecovering the cyanuricchloride.

3. The method of claim 1`in which the mixture is maintained at atemperature within the range of 20-40 C.

4. The method of claim 1 in which the reaction mixture is maintained ata temperature between about 20 and 40 C., separating cyanuric chloridefrom the mixture and reusing the remaining liquor ln a subsequent run bybringing cyanogen chloride into contact with said liquor.

6. The method of claim 1 in which the diluent is a mixture of dioxaneand chloroform.

JACK T. THURSTON.

REFERENCES CITED The following references are of record in the iile ofthis patent:

UNITED STATES PATENTS Number Name Date 2,286,129 Veltman June 9, 1942FOREIGN PATENTS Number Country Date 399,464 Canadian 1941 OTHERREFERENCES Oflicial Gazette 544, 0. G. 458 and 459.

Catalysis by Berkman (copy in Division 3)I 1940, pages 958, 959, 962,963, 964, 965, 966, 967, 968, 969, 971, 984.

